The influence of grazing on seed production and dispersal in grasslands
Grazing influences morphogenesis as well as physiology of range plants. The objective of this study was to review the international bibliography about seed production and dispersal in grasslands. The selective grazing is one of the most important factors that influences the composition of vegetation in grasslands, as far as it causes mortality of the plants, limitation of growth of young individuals and in general the reduction of tolerance of species, with direct and indirect ways. The effects of grazing on plants include seed dispersal.
Long term effects of grazing on plant biodiversity in grasslands
The effects of long term grazing on plant biodiversity of several grasslands were studied in northern Greece. Five grasslands were selected, three at the elevation zone (100-600m altitude) and two at the higher elevation zone (600-1200m). The vegetation composition, the frequency appearance and richness of the species were measured for all grasslands and the index of similarity was determined. The results indicated that there was similarity between the low and higher altitude grasslands under heavy grazing. The dominant species are proposed to be used as key species for the heavily grazed grasslands.
Grassland production and forage quality in two different climatological environments of Ioannina prefecture
The study was conducted at two sites of Greece: 1) Katsikas (low elevation zone) and 2) Metsovo (high elevation zone). At every site, two experimental plots (500m2 each one) were established: a) not grazed and b) grazed, each one having eight plots, corresponding to eight harvest dates, and four replications. At every harvest date, the biomass production, the proportion of new biomass to litter, the crude protein and the crude fiber content were measured. At the harvest date that biomass production was maximum, the proportion between grasses, legumes, other forbs and litter was also measured. The production of new biomass was maximum in May at the low elevation site (5570 kgr/ha) and in June at the high elevation site (3780 kg/ha). The grazing percentage at the low site did not exceed 50% during the month of maximum production. Grasses dominated at both grazed and not grazed plots in both sites, followed by legumes at the low site, while by forbs at the high one. The crude protein was higher in the grazed plot comparing to the protected one and had the maximum value during spring in the low elevation site, while during early summer in the high elevation site. On the contrary, crude fiber had the lowest value in spring in both sites.
A study on the effect of grazing to microarthropod composition in pastures
The possible effect of grazing in qualitative and quantitative composition of acari-fauna was studied on pastures in the prefecture of Ioannina, Epirus, Greece for the period April 1997-March 1998. The number of species was found to be similar both in the grazed and ungrazed pastures and comprised approximately by 59 and 71 taxa respectively. The most characteristic species were: a) for the grazed pasture: Tyrophagus longior, Oribatuloidea(-Zygoribatula sp.) and immature stages of Cryptostigmata which found dominant and were constant, Steneotarsonemus konoi dominant and accesory, Tarsonemus nr lacustris influent and constant, Zygoribatula sp and Microtydeus bellus influent and accesory; b) for the ungrazed pasture: Tyrophagus longior, Zygoribatula sp. and immatures stages of Cryptostigmata were found dominant and constant, Oribatuloidea(-Zygoribatula sp.) and Steneotarsonemus konoi dominant and accesory, Tarsonemus nr lacustris influent and constant, Peloptulus sp. and Microtydeus bellus influent and accesoty. No significant differences were found during the experiment period between the grazed and ungrazed pasture.
Seasonal fluctuation of microarthropods in grazed and ungrazed pastures, in Ioannina prefecture, Greece
The study of the seasonal fluctuation of the most characteristic acarine taxa found on grazed and ungrazed pastures in Ioannina prefecture, Epirus, Greece during the period April 1997-March 1998 showed the following: Tyrophagus longior reached highest population densities during winter especially on the ungrazed pasture. Immature stages of Cryptostigmata showed higher population densities in August on both pastures with higher number on the grazed one. Zygoribatula sp. showed higher population during winter while the rest of Oribatuloidea during the end of the summer. Tarsonemus nr lacustris reached highest densities in June for the ungrazed pasture, while high numbers for the grazed one occurred in November.
